pg_upgrade

Name

pg_upgrade -- upgrade a PostgreSQL server instance

Synopsis

pg_upgrade-boldbindir-Bnewbindir-dolddatadir-Dnewdatadir [option...]

Description

pg_upgrade (formerly called
pg_migrator) allows data stored
in PostgreSQL data files to be
upgraded to a later PostgreSQL
major version without the data dump/reload typically required for
major version upgrades, e.g. from 8.4.7 to the current major
release of PostgreSQL. It is not
required for minor version upgrades, e.g. from 9.0.1 to
9.0.4.

Major PostgreSQL releases regularly add new features that
often change the layout of the system tables, but the internal
data storage format rarely changes. pg_upgrade uses this fact to perform rapid
upgrades by creating new system tables and simply reusing the old
user data files. If a future major release ever changes the data
storage format in a way that makes the old data format
unreadable, pg_upgrade will not
be usable for such upgrades. (The community will attempt to avoid
such situations.)

pg_upgrade does its best to
make sure the old and new clusters are binary-compatible, e.g. by
checking for compatible compile-time settings, including
32/64-bit binaries. It is important that any external modules are
also binary compatible, though this cannot be checked by
pg_upgrade.

pg_upgrade supports upgrades from 8.3.X and later to the
current major release of PostgreSQL, including snapshot and alpha
releases.

Options

pg_upgrade accepts the
following command-line arguments:

-bold_bindir--old-bindir=old_bindir

the old cluster executable directory; environment
variable PGBINOLD

-Bnew_bindir--new-bindir=new_bindir

the new cluster executable directory; environment
variable PGBINNEW

-c--check

check clusters only, don't change any data

-dold_datadir--old-datadir=old_datadir

the old cluster data directory; environment variable
PGDATAOLD

-Dnew_datadir--new-datadir=new_datadir

the new cluster data directory; environment variable
PGDATANEW

-k--link

use hard links instead of copying files to the new
cluster

-ooptions--old-optionsoptions

options to be passed directly to the old postgres command

-Ooptions--new-optionsoptions

options to be passed directly to the new postgres command

-pold_port_number--old-port=old_portnum

the old cluster port number; environment variable
PGPORTOLD

-Pnew_port_number--new-port=new_portnum

the new cluster port number; environment variable
PGPORTNEW

-r--retain

retain SQL and log files even after successful
completion

-uuser_name--user=user_name

cluster's super user name; environment variable
PGUSER

-v--verbose

enable verbose internal logging

-V--version

display version information, then exit

-?-h--help

show help, then exit

Usage

These are the steps to perform an upgrade with pg_upgrade:

Optionally move the old cluster

If you are using a version-specific installation
directory, e.g. /opt/PostgreSQL/9.1, you do not need to
move the old cluster. The graphical installers all use
version-specific installation directories.

If your installation directory is not version-specific,
e.g. /usr/local/pgsql, it is
necessary to move the current PostgreSQL install directory
so it does not interfere with the new PostgreSQL installation. Once the
current PostgreSQL server
is shut down, it is safe to rename the PostgreSQL
installation directory; assuming the old directory is
/usr/local/pgsql, you can do:

mv /usr/local/pgsql /usr/local/pgsql.old

to rename the directory.

For source installs, build the new
version

Build the new PostgreSQL source with configure flags that are compatible with the
old cluster. pg_upgrade
will check pg_controldata to make
sure all settings are compatible before starting the
upgrade.

Install the new PostgreSQL binaries

Install the new server's binaries and support files.

For source installs, if you wish to install the new
server in a custom location, use the prefix variable:

gmake prefix=/usr/local/pgsql.new install

Install pg_upgrade and pg_upgrade_support

Install the pg_upgrade
binary and pg_upgrade_support library in the new
PostgreSQL cluster.

Initialize the new PostgreSQL cluster

Initialize the new cluster using initdb. Again, use compatible initdb flags that match the old cluster.
Many prebuilt installers do this step automatically. There
is no need to start the new cluster.

Install custom shared object files

Install any custom shared object files (or DLLs) used by
the old cluster into the new cluster, e.g. pgcrypto.so, whether they are from
contrib or some other source. Do
not install the schema definitions, e.g. pgcrypto.sql, because these will be
upgraded from the old cluster.

Adjust authentication

pg_upgrade will connect to the
old and new servers several times, so you might want to set
authentication to peer in
pg_hba.conf or use a ~/.pgpass file (see Section 31.15).

Stop both servers

Make sure both database servers are stopped using, on
Unix, e.g.:

pg_ctl -D /opt/PostgreSQL/8.4 stop
pg_ctl -D /opt/PostgreSQL/9.0 stop

or on Windows, using the proper service names:

NET STOP postgresql-8.4
NET STOP postgresql-9.0

or

NET STOP pgsql-8.3 (PostgreSQL 8.3 and older used a different service name)

Run pg_upgrade

Always run the pg_upgrade binary of the new server,
not the old one. pg_upgrade requires the specification
of the old and new cluster's data and executable
(bin) directories. You can also
specify user and port values, and whether you want the data
linked instead of copied (the default).

If you use link mode, the upgrade will be much faster
(no file copying), but you will not be able to access your
old cluster once you start the new cluster after the
upgrade. Link mode also requires that the old and new
cluster data directories be in the same file system. See
pg_upgrade --help for a full list
of options.

For Windows users, you must be logged into an
administrative account, and then start a shell as the
postgres user and set the proper
path:

Once started, pg_upgrade will
verify the two clusters are compatible and then do the
upgrade. You can use pg_upgrade
--check to perform only the checks, even if the old
server is still running. pg_upgrade
--check will also outline any manual adjustments you
will need to make after the upgrade. If you are going to be
using link mode, you should use the --link option with --check to enable link-mode-specific checks.
pg_upgrade requires write
permission in the current directory.

Obviously, no one should be accessing the clusters
during the upgrade. pg_upgrade defaults to running servers
on port 50432 to avoid unintended client connections. You
can use the same port number for both clusters when doing
an upgrade because the old and new clusters will not be
running at the same time. However, when checking an old
running server, the old and new port numbers must be
different.

If an error occurs while restoring the database schema,
pg_upgrade will exit and you will
have to revert to the old cluster as outlined in step 14 below.
To try pg_upgrade again, you will
need to modify the old cluster so the pg_upgrade schema
restore succeeds. If the problem is a contrib module, you
might need to uninstall the contrib module from the old
cluster and install it in the new cluster after the
upgrade, assuming the module is not being used to store
user data.

Restore pg_hba.conf

If you modified pg_hba.conf,
restore its original settings. It might also be necessary
to adjust other configuration files in the new cluster to
match the old cluster, e.g. postgresql.conf.

Post-Upgrade processing

If any post-upgrade processing is required, pg_upgrade
will issue warnings as it completes. It will also generate
script files that must be run by the administrator. The
script files will connect to each database that needs
post-upgrade processing. Each script should be run
using:

psql --username postgres --file script.sql postgres

The scripts can be run in any order and can be deleted
once they have been run.

Caution

In general it is unsafe to access tables
referenced in rebuild scripts until the rebuild
scripts have run to completion; doing so could
yield incorrect results or poor performance. Tables
not referenced in rebuild scripts can be accessed
immediately.

Statistics

Because optimizer statistics are not transferred by
pg_upgrade, you will be instructed
to run a command to regenerate that information at the end
of the upgrade.

Delete old cluster

Once you are satisfied with the upgrade, you can delete
the old cluster's data directories by running the script
mentioned when pg_upgrade
completes. You can also delete the old installation
directories (e.g. bin, share).

Reverting to old cluster

If, after running pg_upgrade,
you wish to revert to the old cluster, there are several
options:

If you ran pg_upgrade with
--check, no modifications were
made to the old cluster and you can re-use it
anytime.

If you ran pg_upgrade with
--link, the data files are
shared between the old and new cluster. If you started
the new cluster, the new server has written to those
shared files and it is unsafe to use the old
cluster.

If you ran pg_upgradewithout--link or did not start the new
server, the old cluster was not modified except that,
if linking started, a .old
suffix was appended to $PGDATA/global/pg_control. To reuse the
old cluster, possibly remove the .old suffix from $PGDATA/global/pg_control; you can then
restart the old cluster.

Notes

pg_upgrade does not support
upgrading of databases containing these reg* OID-referencing system data types: regproc, regprocedure,
regoper, regoperator,
regconfig, and regdictionary. (regtype can be
upgraded.)

All failure, rebuild, and reindex cases will be reported by
pg_upgrade if they affect your
installation; post-upgrade scripts to rebuild tables and indexes
will be generated automatically.

For deployment testing, create a schema-only copy of the old
cluster, insert dummy data, and upgrade that.

If you are upgrading a pre-PostgreSQL 9.2 cluster that uses a
configuration-file-only directory, you must pass the real data
directory location to pg_upgrade, and pass the configuration
directory location to the server, e.g. -d
/real-data-directory -o '-D /configuration-directory'.

If using a pre-9.1 old server that is using a non-default
Unix-domain socket directory or a default that differs from the
default of the new cluster, set PGHOST to
point to the old server's socket location. (This is not relevant
on Windows.)

A Log-Shipping Standby Server (Section 25.2) cannot be upgraded because
the server must allow writes. The simplest way is to upgrade the
primary and use rsync to rebuild the
standbys. You can run rsync while the
primary is down, or as part of a base backup (Section
24.3.2) which overwrites the old standby cluster.

If you want to use link mode and you do not want your old
cluster to be modified when the new cluster is started, make a
copy of the old cluster and upgrade that in link mode. To make a
valid copy of the old cluster, use rsync
to create a dirty copy of the old cluster while the server is
running, then shut down the old server and run rsync again to update the copy with any changes to
make it consistent. You might want to exclude some files, e.g.
postmaster.pid, as documented in
Section
24.3.3.

Limitations in Upgrading from PostgreSQL 8.3

Upgrading from
PostgreSQL 8.3 has additional restrictions not present when
upgrading from later PostgreSQL releases. For example,
pg_upgrade will not work for upgrading from 8.3 if a user
column is defined as:

a tsquery data type

data type name and is not the
first column

You must drop any such columns and upgrade them
manually.

pg_upgrade will not work if the ltree contrib module is installed in a
database.

pg_upgrade will require a table rebuild if:

a user column is of data type tsvector

pg_upgrade will require a reindex if:

an index is of type hash or GIN

an index uses bpchar_pattern_ops

Also, the default datetime storage format changed to integer
after PostgreSQL 8.3.
pg_upgrade will check that the datetime storage format used by
the old and new clusters match. Make sure your new cluster is
built with the configure flag --disable-integer-datetimes.

For Windows users, note that due to different integer
datetimes settings used by the graphical installer and the MSI
installer, it is only possible to upgrade from version 8.3 of
the installer distribution to version 8.4 or later of the
installer distribution. It is not possible to upgrade from the
MSI installer to the new graphical installer.